Well, it looks like the main issue with the particle system (the Big Yellow Line) is gone, and the little chaps are now being successfully rendered... far in the distance, behind the player's ship. I think this is due to some weirdness around MMULT which BigPEmu doesn't entirely replicate. Here's another build with a potential fix.

Also in this release is a small change to the controls. While B ("lock direction and fire") is held down, you can use 4 and 6 to rotate your ship. On the Pro Controller these of course map to the left and right triggers, but on a normal controller it's a finger-breaking combination, which is why I hesitated to add them. Users with trigger buttons are at a definite advantage now.